The Government has been slammed for selling a valuable database of every British postcode and address in last year's flotation of the Royal Mail.

Ministers were strongly criticised for including the register, which contains 1.8 million postcodes and all 28 million addresses, to help boost the share price in the initial public offering (IPO).

The cross-party Commons Public Administration Committee said the Postcode Address File (PAF) was a "national asset" which should have been retained and made publicly available to benefit businesses and the economy.

It said the PAF's sale achieved only "short-term gain" in last autumn's IPO and was an "unacceptable and unnecessary consequence of privatisation".

The committee said losing the database to the private sector has the potential to thwart economic innovation and growth.

Unions were highly critical of the Royal Mail privatisation

Committee chairman Bernard Jenkin said: "The sale of the PAF with the Royal Mail was a mistake. Public access to public sector data must never be sold or given away again."

The PAF holds all known Royal Mail delivery points in the UK and the committee said an immense amount of work went into collecting the database and said it was of "huge direct value" to the economy.

In a statement to Sky News, the Royal Mail defended its position and said it takes its "responsibilities and obligations" for the PAF "very seriously".

It said: "Last year, Ofcom held a review of the PAF’s pricing and licensing framework and recognised the integral relationship between PAF and delivery of the Universal Service Obligation (USO).

"Without positive and progressive management of PAF, our operational ability to deliver the USO would be severely undermined.

"Following its consultation, Ofcom concluded in July 2013 that Royal Mail should continue to be able to recover both the internal and external costs of PAF from licensees.

"In addition, in 2011 Parliament decided that the PAF should be available to all on reasonable terms."